How to find the peak decibel gain of the highest gain channel of a high gain amp?

[R.G.]

Ok, so regardless of how much the sound is distorted, can we achieve a peak decibel gain of say 115 dB or more on the highest gain channels of solid-state amps? If it is possible or impossible, what is the reason?

First, measuring gain regardless of how much the sound is distorted doesn't have any particular meaning. Distortion in general makes the gain look lower, because it involves lopping off peaks and valleys, so that effectively hides any gain that would be measurable. Distortion means you can't accurately measure gain.

Second, decibel gain and just gain are the same thing, just expressed differently. "+115db" has the same meaning as "562,341 times bigger". They're just two ways of expressing exactly the same thing. I am only harping on this because your comments seem to imply that you think decibel gain is different. It's actually a gain (Vout/Vin) of 562,341 expressed differently.

But yes, it's entirely possible to get 115db of gain. The OPAx991 was the first opamp that turned up in my search in Mouser Electronics. It's specified for an open loop gain of 120db minimum, and typically 145db. That's a $3 opamp. A $0.31 opamp, the MCP6486, has a typical open loop gain of 105db, typically 130db. These are simplistic examples, as opamps do have that gain, but generally are not run open loop.

[teemuk]

And if that's not enough cascade an x amount of those.

[thinkingchicken]

Ok, so regardless of how much the sound is distorted, can we achieve a peak decibel gain of say 115 dB or more on the highest gain channels of solid-state amps? If it is possible or impossible, what is the reason?

First, measuring gain regardless of how much the sound is distorted doesn't have any particular meaning. Distortion in general makes the gain look lower, because it involves lopping off peaks and valleys, so that effectively hides any gain that would be measurable. Distortion means you can't accurately measure gain.

Second, decibel gain and just gain are the same thing, just expressed differently. "+115db" has the same meaning as "562,341 times bigger". They're just two ways of expressing exactly the same thing. I am only harping on this because your comments seem to imply that you think decibel gain is different. It's actually a gain (Vout/Vin) of 562,341 expressed differently.

But yes, it's entirely possible to get 115db of gain. The OPAx991 was the first opamp that turned up in my search in Mouser Electronics. It's specified for an open loop gain of 120db minimum, and typically 145db. That's a $3 opamp. A $0.31 opamp, the MCP6486, has a typical open loop gain of 105db, typically 130db. These are simplistic examples, as opamps do have that gain, but generally are not run open loop.

Alright, so we can say we can make both tubes and solid-state gain stages to reach 115 dB or more. Isn't it?

Is there a limit to how much we can increase the peak decibel gain of both tube-based and solid-state based gain stage? What is the highest hypothetical decibel gain that we can achieve with both tube and solid-state based gain stage?

[thinkingchicken]

And if that's not enough cascade an x amount of those.

You mean that mentioned opamp?

[teemuk]

Yes, I mean the opamp operated without feedback. I suggest you first try just a single stage in practice to find out if that's enough of gain.

Ok, so regardless of how much the sound is distorted, can we achieve a peak decibel gain of say 115 dB or more on the highest gain channels of solid-state amps?

Yes. But in practive we need the amps to sound good and have very little use for incomprehensible noise generators. One only needs so and so much of gain to amplify the weak pickup signal to ridiculous amounts of distortion. Past that it's just diminishing return and pumping up the noise-to-signal ratio.

If it is possible or impossible, what is the reason?

Totally possible but pointless. Try that open loop opamp.

Meditate on this:

First, measuring gain regardless of how much the sound is distorted doesn't have any particular meaning. Distortion in general makes the gain look lower, because it involves lopping off peaks and valleys, so that effectively hides any gain that would be measurable. Distortion means you can't accurately measure gain.

In practice, at the point where the signal clips producing a "square wave" output at every positive and negative lobe of the input waveform adding more and more gain adds nothing. Nothing. The distortion is at its ceiling. Even a gain control will do nothing when its range is from maximum distortion to maximum distortion. Gain is easy to acquire but excessive amounts are just stupid design. In practice we don't need astronomical gain ratios.

[teemuk]

Continuing to that, a comparator is a circuit that is devised to saturate to its maximum positive or negative voltage output, "ceiling", whenever its input signal flips to corresponding polarity. That circuit is all you ever need to clipping distort guitar's input signal as much as practically possible.

Guess what this comparator circuit is? It's an open loop opamp with its ridiculously high gain.

Haven't we had this conversation on one or two other forums already? I've said my share and unless you bring some worthwhile content to this thread I'm done with the topic.

[thinkingchicken]

Yes, I mean the opamp operated without feedback. I suggest you first try just a single stage in practice to find out if that's enough of gain.

Ok, so regardless of how much the sound is distorted, can we achieve a peak decibel gain of say 115 dB or more on the highest gain channels of solid-state amps?

Yes. But in practive we need the amps to sound good and have very little use for incomprehensible noise generators. One only needs so and so much of gain to amplify the weak pickup signal to ridiculous amounts of distortion. Past that it's just diminishing return and pumping up the noise-to-signal ratio.

If it is possible or impossible, what is the reason?

Totally possible but pointless. Try that open loop opamp.

Meditate on this:

First, measuring gain regardless of how much the sound is distorted doesn't have any particular meaning. Distortion in general makes the gain look lower, because it involves lopping off peaks and valleys, so that effectively hides any gain that would be measurable. Distortion means you can't accurately measure gain.

In practice, at the point where the signal clips producing a "square wave" output at every positive and negative lobe of the input waveform adding more and more gain adds nothing. Nothing. The distortion is at its ceiling. Even a gain control will do nothing when its range is from maximum distortion to maximum distortion. Gain is easy to acquire but excessive amounts are just stupid design. In practice we don't need astronomical gain ratios.

Continuing to that, a comparator is a circuit that is devised to saturate to its maximum positive or negative voltage output, "ceiling", whenever its input signal flips to corresponding polarity. That circuit is all you ever need to clipping distort guitar's input signal as much as practically possible.

Guess what this comparator circuit is? It's an open loop opamp with its ridiculously high gain.

Haven't we had this conversation on one or two other forums already? I've said my share and unless you bring some worthwhile content to this thread I'm done with the topic.

Yes, we've been discussing about this but then I got really confused especially when HotBluePlate said it is somehow impossible for solid-state devices such as distortion pedals to get higher decibel gain than the peak decibel gain of high gain tube amps because of some differences between how tube amps and distortion pedals work.

So, lets see if I get it right so we can get rid of any confusion, so the conclusion is we can easily adjust the peak decibel gain of both tube amps and solid-state amps to any amount that we like.

I'm asking because people can apparently order a custom made amp or distortion pedal from amp makers and pedal makers, so I wonder if someone had actually build something like a distortion pedal but with a very high decibel gain maybe around 150 dB or more. I believe it will sounds like the video below:

[thinkingchicken]

Also, I wonder how much decibel gain this thing have. Must be too high. This is basically a tube preamp without the power amp. I imagine this is what happen if someone turn the gain knob to max and add more gain to the existing gain stages.

[R.G.]

Yes, we've been discussing about this but then I got really confused especially when HotBluePlate said it is somehow impossible for solid-state devices such as distortion pedals to get higher decibel gain than the peak decibel gain of high gain tube amps because of some differences between how tube amps and distortion pedals work.

(1) Did you ask HotBluePlate to explain, in detail, why that is?
(2) No slight intended to HotBluePlate, but what are his/her credentials to make that claim?
(3) Did you read my explanation above about the fact that it's the practical difficulties involved in noise and oscillation avoidance that limit gain?
(4) Are you familiar with the Dunning-Kruger phenomena?

So, lets see if I get it right so we can get rid of any confusion, so the conclusion is we can easily adjust the peak decibel gain of both tube amps and solid-state amps to any amount that we like.

Add any amount of gain? Yes.
Easily? No. Keeping it from oscillating or being a roaring, hissing cascade of noise gets harder and harder as you add gain. This is true for all gain devices, tube and solid state.

I'm asking because people can apparently order a custom made amp or distortion pedal from amp makers and pedal makers, so I wonder if someone had actually build something like a distortion pedal but with a very high decibel gain maybe around 150 dB or more.

Apparently? Sure.
How would they know that what they got was really that amount of gain? I outlined the difficulty in actually measuring high gains. How would you know you got a 150db gain pedal or amp, instead of only a 100db gain amp.
There is sometimes a difference in actual gain (volts out divided by volts in) and advertising gain.

And again DISTORTION IS NOT GAIN per se. When a guitarist, especially on an internet pedal or amp forum says "gain" they almost always mean distortion, not gain. When gain comes up, it's nearly always distortion that's wanted. Which of these do you mean?

[thinkingchicken]

Yes, we've been discussing about this but then I got really confused especially when HotBluePlate said it is somehow impossible for solid-state devices such as distortion pedals to get higher decibel gain than the peak decibel gain of high gain tube amps because of some differences between how tube amps and distortion pedals work.

(1) Did you ask HotBluePlate to explain, in detail, why that is?
(2) No slight intended to HotBluePlate, but what are his/her credentials to make that claim?
(3) Did you read my explanation above about the fact that it's the practical difficulties involved in noise and oscillation avoidance that limit gain?
(4) Are you familiar with the Dunning-Kruger phenomena?

So, lets see if I get it right so we can get rid of any confusion, so the conclusion is we can easily adjust the peak decibel gain of both tube amps and solid-state amps to any amount that we like.

Add any amount of gain? Yes.
Easily? No. Keeping it from oscillating or being a roaring, hissing cascade of noise gets harder and harder as you add gain. This is true for all gain devices, tube and solid state.

I'm asking because people can apparently order a custom made amp or distortion pedal from amp makers and pedal makers, so I wonder if someone had actually build something like a distortion pedal but with a very high decibel gain maybe around 150 dB or more.

Apparently? Sure.
How would they know that what they got was really that amount of gain? I outlined the difficulty in actually measuring high gains. How would you know you got a 150db gain pedal or amp, instead of only a 100db gain amp.
There is sometimes a difference in actual gain (volts out divided by volts in) and advertising gain.

And again DISTORTION IS NOT GAIN per se. When a guitarist, especially on an internet pedal or amp forum says "gain" they almost always mean distortion, not gain. When gain comes up, it's nearly always distortion that's wanted. Which of these do you mean?

HotBluePlate seems to be an amp builder, not sure. He said it is due to the voltage that a distortion pedal possessed, something like that. Our discussion can be seen in the link I posted earlier which is in the TheGearPage forum. No, I'm not familiar with Dunning Kruger phenomena.

Tbh, it does not matter if it ends up becoming a noise generator because I'm trying to experiment with harsh noise "music". As long as the peak decibel gain is beyond 140 dB or more, it is just fine it is just this curiosity about how will something with a peak decibel gain of 140 decibel or beyond will sound like. I believe it will sound just like the two videos I recently posted.

Usually people equating gain with distortion, but this is not always the case if I'm not mistaken. But the more gain, the more clipped the waves become because of the limiting headroom. Correct?

[R.G.]

HotBluePlate seems to be an amp builder, not sure. He said it is due to the voltage that a distortion pedal possessed, something like that.

I'll go look at the conversation. I've heard that rationale before, and I disagree with it. When I discovered it before, (again, not bad-mouthing HotBluePlate, I'll go read the conversation) the rationale went something like "Tubes have much bigger power supply voltage, hundreds of volts, so they can amplify up signal to bigger voltages than pedals with a limited 9V power supply." This is a mishmash of the reality. Having hundreds of volts of power supply "headroom" does mean that you can make bigger undistorted signals. That really doesn't help much when (1) the signal to the speakers is limited to whatever the output watts into the speaker load is and (2) the "gain" is to be used for distortion anyways.
Let's assume that a tube preamp makes a 200V signal. A 9V pedal might make an 8 volt signal. 200V/8V = 25. Converting 25 to db gets you 28db more >>UNDISTORTED<< signal level. So the advantage is to the tube by 28db, right?
Wrong. Voltage swing is not gain, and that's not distortion. The tube circuit and the pedal can have exactly the same >>gain<< but the pedal starts distorting 28db sooner than the tube circuit. One way of looking at this is that the pedal distorts more by 28db.
For a typical 100mv single coil guitar output, +115 db is an output voltage of 0.100V X 562,341 = 56,234V. Neither the tube circuit nor the pedal is going to reproduce that cleanly, so both will distort by limiting or clipping when limited by their power supply. The pedal will distort earlier than the tube circuit and will seem to have more "gain", but really will have just more distortion because it started distorting 28 db earlier than the tube circuit.
If you really want more gain, put a distortion pedal in front of an amp. Now you can get your 100+ db from the distortion pedal and another 100+ db from the amp. Wow! You now have 200 db of gain! Is that better, and if so, how?

No, I'm not familiar with Dunning Kruger phenomena.

It's an interesting concept. I think you'd enjoy reading about it. Wikipedia has a good write up on it. It explains a huge amount of the "experts" dispensing advice on the internet.

Tbh, it does not matter if it ends up becoming a noise generator because I'm trying to experiment with harsh noise "music". As long as the peak decibel gain is beyond 140 dB or more, it is just fine it is just this curiosity about how will something with a peak decibel gain of 140 decibel or beyond will sound like. I believe it will sound just like the two videos I recently posted.

Good luck on your quest. The simplest way to do that is to stack a pedal in front of an amp and turn up both gains until you get what you like.

Usually people equating gain with distortion, but this is not always the case if I'm not mistaken.

It is never the case. Hearing someone equate gain with distortion signals that the person doesn't really understand either one.

But the more gain, the more clipped the waves become because of the limiting headroom. Correct?

In the simplest possible case, yes. But the actual distortion can be achieved by other ways without large power supply headroom, as i explained above. In fact, relying on the power supply voltage for clipping gives tube amps a disadvantage in getting more distortion. There are other, and often better sounding, ways to distort. Distortion is not gain. Gain and power supply voltage is one of many ways to get distortion.

[R.G.]

I read the discussion. Both HotBuePlates and Teemuk's comments in that thread are exactly in line with what I'm saying. HotBluePlates even states what I re-capped: gain is not distortion and distortion is not gain.

Kudos to both HotBluePlates and Teemuk for what they're trying to do in that thread. You might want to re-read it closely.

[pdf64]

How about quantifying the depth of distortion available by referring the clipping voltage back to the input?
eg an MXR Distortion +, with a max gain of about 200 and clipping voltage of 0.6Vpk = 0.42V rms, should clip signals above about 2mV rms.
https://el34world.com/charts/Schematics ... t_plus.pdf

Fender started doing something similar from the late 70s (Ed Jahns era) onwards, but using a specific power output rather than preamp clipping.
https://el34world.com/charts/Schematics ... _schem.pdf

[thinkingchicken]

HotBluePlate seems to be an amp builder, not sure. He said it is due to the voltage that a distortion pedal possessed, something like that.

I'll go look at the conversation. I've heard that rationale before, and I disagree with it. When I discovered it before, (again, not bad-mouthing HotBluePlate, I'll go read the conversation) the rationale went something like "Tubes have much bigger power supply voltage, hundreds of volts, so they can amplify up signal to bigger voltages than pedals with a limited 9V power supply." This is a mishmash of the reality. Having hundreds of volts of power supply "headroom" does mean that you can make bigger undistorted signals. That really doesn't help much when (1) the signal to the speakers is limited to whatever the output watts into the speaker load is and (2) the "gain" is to be used for distortion anyways.
Let's assume that a tube preamp makes a 200V signal. A 9V pedal might make an 8 volt signal. 200V/8V = 25. Converting 25 to db gets you 28db more >>UNDISTORTED<< signal level. So the advantage is to the tube by 28db, right?
Wrong. Voltage swing is not gain, and that's not distortion. The tube circuit and the pedal can have exactly the same >>gain<< but the pedal starts distorting 28db sooner than the tube circuit. One way of looking at this is that the pedal distorts more by 28db.
For a typical 100mv single coil guitar output, +115 db is an output voltage of 0.100V X 562,341 = 56,234V. Neither the tube circuit nor the pedal is going to reproduce that cleanly, so both will distort by limiting or clipping when limited by their power supply. The pedal will distort earlier than the tube circuit and will seem to have more "gain", but really will have just more distortion because it started distorting 28 db earlier than the tube circuit.
If you really want more gain, put a distortion pedal in front of an amp. Now you can get your 100+ db from the distortion pedal and another 100+ db from the amp. Wow! You now have 200 db of gain! Is that better, and if so, how?

No, I'm not familiar with Dunning Kruger phenomena.

It's an interesting concept. I think you'd enjoy reading about it. Wikipedia has a good write up on it. It explains a huge amount of the "experts" dispensing advice on the internet.

Tbh, it does not matter if it ends up becoming a noise generator because I'm trying to experiment with harsh noise "music". As long as the peak decibel gain is beyond 140 dB or more, it is just fine it is just this curiosity about how will something with a peak decibel gain of 140 decibel or beyond will sound like. I believe it will sound just like the two videos I recently posted.

Good luck on your quest. The simplest way to do that is to stack a pedal in front of an amp and turn up both gains until you get what you like.

Usually people equating gain with distortion, but this is not always the case if I'm not mistaken.

It is never the case. Hearing someone equate gain with distortion signals that the person doesn't really understand either one.

But the more gain, the more clipped the waves become because of the limiting headroom. Correct?

In the simplest possible case, yes. But the actual distortion can be achieved by other ways without large power supply headroom, as i explained above. In fact, relying on the power supply voltage for clipping gives tube amps a disadvantage in getting more distortion. There are other, and often better sounding, ways to distort. Distortion is not gain. Gain and power supply voltage is one of many ways to get distortion.

I read the discussion. Both HotBuePlates and Teemuk's comments in that thread are exactly in line with what I'm saying. HotBluePlates even states what I re-capped: gain is not distortion and distortion is not gain.

Kudos to both HotBluePlates and Teemuk for what they're trying to do in that thread. You might want to re-read it closely.

I see, I see. Thank you so much for your explanations. Really appreciate it. It's been really helpful, a lot of valuable informations.

How about quantifying the depth of distortion available by referring the clipping voltage back to the input?
eg an MXR Distortion +, with a max gain of about 200 and clipping voltage of 0.6Vpk = 0.42V rms, should clip signals above about 2mV rms.
https://el34world.com/charts/Schematics ... t_plus.pdf

Fender started doing something similar from the late 70s (Ed Jahns era) onwards, but using a specific power output rather than preamp clipping.
https://el34world.com/charts/Schematics ... _schem.pdf

Sorry, is the max gain of MXR Distortion + decibel gain or amplification factor?

[romberg]

It is possible to distort a signal to the point that adding more distortion is undetectable. This video always makes me chuckle for some reason .